Measurements

Contents
1 Introduction 1
2 Fundamentals 7
2.1 Structural Properties of Microcrystalline Silicon .......... 7
2.2 Electronic Density of States ..................... 9
2.2.1 Band-Tail States ...................... 10
2.2.2 Deep Defects ........................ 11
2.3 Charge Carrier Transport ...................... 14
2.3.1 Barrier Limited Transport ................. 15
2.3.2 Dispersive Transport in Disordered Semiconductors . . . 15
3 Sample Preparation and Characterization 19
3.1 Characterization Methods ...................... 19
3.1.1 Raman Spectroscopy .................... 19
3.1.2 Electron Spin Resonance (ESR) .............. 21
3.1.3 Electrical Conductivity ................... 24
3.1.4 Transient Photocurrent Measurements (TOF) ....... 24
3.1.5 Thickness Measurements .................. 30
3.2 Deposition Technique ........................ 32
3.2.1 Plasma-Enhanced Chemical Vapor Deposition (PECVD) . 32
3.2.2 Hot-Wire Chemical Vapor Deposition (HWCVD) ..... 33
3.3 Sample Preparation ......................... 34
3.3.1 Sample Preparation for ESR and conductivity measurements 35
3.3.2 PIN-Diodes for Transient Photocurrent Measurements . . 36
4 Intrinsic Microcrystalline Silicon 39
4.1 Raman Spectroscopy ........................ 39
4.2 Electrical Conductivity ....................... 41
4.3 ESR Signals and Paramagnetic States in Intrinsic µc-Si:H ..... 42
4.4 Discussion - Relation between ESR- and Structural Properties . . 47
4.5 Summary .............................. 50
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